Dual-Tree Complex Wavelet Transform Pack - version 2.2 - update Nick Kingsbury and Cian Shaffrey, Cambridge University, February 2001. Version 2.0 files (dated August 2000) have been optimised for speed and memory use, principally by performing column filtering with CONV2 instead of row filtering (which is significantly slower) and by avoiding unneccessary copying of matrices within functions. The ROWFILT functions have been replaced by COLFILT equivalents, and some lower level functions have been removed. Version 2.1 files (dated Sept 2000) contain 2 new functions, CWTBAND6 and ICWTBAND6, and some bugs in the comments of other files have been corrected. These new functions provide a more convenient way to handle complete sets of 6 complex bandpass subbands from a given level of the transform. Version 2.2 UPDATE: A few bug were identifed and fixed. These mainly related to the subband extraction routines and filter design. An extra Q-shift filter has been added - qshift_06. This filter is a 10,10 tap filter with only 6,6 non-zero taps. Also included is a JPEG image that helps demonstrate the orientationly selective nature of the DTCWT - The image, called wavelet_orien.jpg, can be used instead of lenna.mat. The tests are detailed in Testing.txt. The main functions: dtwavedec => 1D DTCWT decomposition dtwaverec => 1D DTCWT reconstruction cwtband => Extracts individual subbands from the result of DTWAVEDEC at specified levels icwtband => Allows insertion of individual subbands into the input vector for DTWAVEREC. dtwavedec2 => 2D DTCWT decomposition dtwaverec2 => 2D DTCWT reconstruction cwtband2 => Extracts individual subimages from the result of DTWAVEDEC2 at specified levels icwtband2 => Allows insertion of individual subimages into the input vector for DTWAVEREC2 cwtband6 => Extracts a set of 6 subimages from the result of DTWAVEDEC2 at specified levels icwtband6 => Allows insertion of a set of 6 subimages into the input vector for DTWAVEREC2. Lower level functions: colfilt => Column filtering of a matrix with symmetric extension coldfilt => Column filtering with decimation by 2. colifilt => Column filtering with interpolation (upsampling) by 2. reflect => Reflect a vector about max and min limits (used for sym extension). draw => Draw an image in a correctly sized figure window. cimage5 => Draw a complex subimage using a colour palette for the complex numbers. Various .MAT files contain the complex wavelet filter coefficients. To test the DTCWT package please read the TESTING.TXT file. ******************************** Further information on the DT CWT can be obtained from papers downloadable from NGK's website (given below). The best tutorial is in the 1999 Royal Society Paper. In particular this explains the conversion between 'real' quad-number subimages and pairs of complex subimages, which is carried out in CWTBAND2 and ICWTBAND2 if 'cplx' is selected as the required subimage mode. The Q-shift filters are explained in the ICIP 2000 paper and the paper for the Journal on Applied Computation and Harmonic Analysis. Cian Shaffrey and Nick Kingsbury, Cambridge University, August 2000 *********************************************************** Dr N G Kingsbury, Dept. of Engineering, University of Cambridge, Trumpington St., Cambridge CB2 1PZ, UK. or Trinity College, Cambridge CB2 1TQ, UK. Phone: (0 or +44) 1223 338514 / 332***7; Home: 1954 211152; Fax: 1223 3385*** / 332662; E-mail: ngk@eng.cam.ac.uk Web home page: http://www.eng.cam.ac.uk/~ngk/ ***********************************************************

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